JP7616507B2 - Glass composition and sealing material - Google Patents

Description

The present invention relates to a glass composition and sealing material that are weather resistant and capable of hermetically sealing at low temperatures.

Sealing materials are used in semiconductor integrated circuits, quartz crystal oscillators, metal components, flat panel displays, glass terminals for LEDs, etc. Sealing materials are required to have chemical durability and heat resistance, so glass-based sealing materials are used instead of resin-based adhesives. Sealing materials are also required to have properties such as mechanical strength, fluidity, and weather resistance. In particular, sealing electronic components equipped with elements that are sensitive to heat requires that the sealing temperature be as low as possible. Specifically, it is required that sealing can be performed at temperatures of 400°C or less. Lead borate glass, which contains a large amount of PbO, which has a large effect of lowering the softening point, has been widely used as a glass that satisfies these properties (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 63-315536 JP 2019-202921 A

In order to reduce the environmental impact, it is desirable to replace lead-borate glass with lead-free glass that does not contain PbO, and various lead-free glasses with low softening points have been developed.

However, in general, when the softening point of glass is low, the weather resistance tends to decrease. Therefore, it is not easy to achieve both a low softening point and high weather resistance. The CuO-TeO ₂ -MoO ₃ glass described in Patent Document 2 is a promising alternative to lead borate glass, and although it has good weather resistance, it cannot be said that its softening point is sufficiently low.

In view of the above, the present invention aims to provide a glass composition and sealing material that have good weather resistance and can be sealed at low temperatures.

As a result of extensive investigations, the present inventors have found that the above problems can be solved by using a specific B ₂ O ₃ -TeO ₂ -MoO ₃ based glass, and propose this as the present invention. That is, the glass composition of the present invention is characterized by containing, in mole percent, 1 to 20% B ₂ O ₃ , 30 to 80% TeO ₂ , and 5 to 30% MoO ₃ .

In addition, the glass composition of the present invention preferably has a content of Li ₂ O + Na ₂ O + K ₂ O of 0 to 30 mol %. Note that "A + B + C" refers to the total amount of component A, component B and component C. For example, "Li ₂ O + Na ₂ O + K ₂ O" refers to the total amount of Li ₂ O, Na ₂ O and K ₂ O.

In addition, the glass composition of the present invention preferably has a content of MgO + CaO + SrO + BaO + ZnO of 0 to 30 mol %.

In addition, the glass composition of the present invention preferably has a TiO ₂ +Al ₂ O ₃ content of 0 to 10 mol %.

The glass composition of the present invention preferably contains, in mol %, CuO 0-30%, WO ₃ 0-20%, P ₂ O ₅ 0-10%, and Fe ₂ O ₃ 0-10%.

The sealing material of the present invention preferably contains 40 to 100% by volume of glass powder made of the above glass composition and 0 to 60% by volume of a fire-resistant filler powder.

In addition, in the sealing material of the present invention, it is preferable that the refractory filler powder is approximately spherical. Here, "approximately spherical" is not limited to a perfect sphere, but refers to a refractory filler powder in which the value obtained by dividing the shortest diameter passing through the center of gravity of the refractory filler powder by the longest diameter is 0.5 or more, preferably 0.7 or more.

In the sealing material of the present invention, all or a part of the refractory filler powder is preferably Zr ₂ WO ₄ (PO ₄ ) ₂ .

The sealing material of the present invention is also preferably used in quartz crystal oscillator packages.

The sealing material paste of the present invention preferably contains the above-mentioned sealing material and a vehicle.

The present invention provides a glass composition and sealing material that have good weather resistance and can be sealed at low temperatures.

FIG. 2 is a schematic diagram showing a measurement curve obtained by a macro-type differential thermal analyzer.

The glass composition of the present invention contains, in mol %, 1-20% B ₂ O ₃ , 30-80% TeO ₂ , and 5-30% MoO ₃ as a glass composition. The reasons for limiting the glass composition range as described above are as follows. In the explanation of the content of each component, "%" means "mol %" unless otherwise specified.

B ₂ O ₃ is a component that forms a glass network. The content of B ₂ O ₃ is 1 to 20%, preferably 2 to 15%, and more preferably 4 to 10%. If the content of B ₂ O ₃ is too low, the weather resistance is likely to decrease. On the other hand, if the content of B ₂ O ₃ is too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult and making the glass more likely to undergo phase separation. Also, vitrification becomes difficult.

_TeO2 is a component that forms a glass network and enhances weather resistance. The content of _TeO2 is 30 to 80%, preferably 40 to 70%, and more preferably 50 to 65%. If the content of _TeO2 is too small, the glass becomes thermally unstable and is prone to devitrification during melting or firing. On the other hand, if the content of _TeO2 is too large, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult and tending to cause the thermal expansion coefficient to become too high.

_MoO3 is a component that forms a glass network. The content of _MoO3 is 5 to 30%, preferably 7 to 27%, more preferably 10 to 25%, further preferably 12 to 22%, and particularly preferably 15 to 20%. If the content of _MoO3 is too small, vitrification becomes difficult, and the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult. On the other hand, if the content of _MoO3 is too large, the glass becomes thermally unstable, and the glass is easily devitrified during melting or firing, and the thermal expansion coefficient tends to become too high.

In addition to the above ingredients, the following ingredients may also be added:

Li ₂ O, Na ₂ O and K ₂ O are components that reduce the viscosity (softening point, etc.) of glass. The content of Li ₂ O + Na ₂ O + K ₂ O is preferably 0 to 30%, more preferably 5 to 25%, and even more preferably 10 to 20%. If the content of Li ₂ O + Na ₂ O + K ₂ O is too small, the viscosity (softening point, etc.) of the glass increases, and sealing at low temperatures may become difficult. In addition, vitrification may become difficult. On the other hand, if the content of Li ₂ O + Na ₂ O + K ₂ O is too large, the glass becomes thermally unstable and is easily devitrified during melting or firing. In addition, the weather resistance tends to decrease and the thermal expansion coefficient tends to become too high.

Li ₂ O is a component that significantly reduces the viscosity (softening point, etc.) of glass compared with Na ₂ O and K ₂ O. The content of Li ₂ O is preferably 0 to 30%, more preferably 1 to 20%, further preferably 3 to 15%, and particularly preferably 5 to 13%. If the content of Li ₂ O is too small, the viscosity (softening point, etc.) of the glass becomes high, and sealing at low temperatures may become difficult. In addition, vitrification may become difficult. On the other hand, if the content of Li ₂ O is too large, the glass becomes thermally unstable and the glass is easily devitrified during melting or firing. In addition, the weather resistance is easily reduced and the thermal expansion coefficient tends to become too high.

Na ₂ O is a component that reduces the viscosity (softening point, etc.) of glass compared with K ₂ O. The content of Na ₂ O is preferably 0 to 20%, more preferably 0 to 15%, further preferably 0 to 10%, and particularly preferably 1 to 7%. If the content of Na ₂ O is too small, the viscosity (softening point, etc.) of the glass becomes high, and sealing at low temperatures may become difficult. In addition, vitrification may become difficult. On the other hand, if the content of Na ₂ O is too large, the glass becomes thermally unstable and the glass is easily devitrified during melting or firing. In addition, the weather resistance is easily reduced and the thermal expansion coefficient tends to become too high.

K ₂ O is a component that reduces the viscosity (softening point, etc.) of glass. The content of K ₂ O is preferably 0 to 30%, more preferably 1 to 20%, further preferably 3 to 15%, and particularly preferably 5 to 13%. If the content of _{K 2} O is too small, the viscosity (softening point, etc.) of the glass increases, which may make sealing at low temperatures difficult. Also, vitrification may become difficult. On the other hand, if the content of K ₂ O is too large, the glass becomes thermally unstable and is easily devitrified during melting or firing. Also, the weather resistance is easily reduced and the thermal expansion coefficient tends to become too high.

The molar ratio Li ₂ O/K ₂ O is preferably 0.3 to 5, more preferably 0.4 to 4, 0.5 to 3, further preferably 0.6 to 2, and particularly preferably 0.7 to 1.5, in order to lower the softening point by the alkali mixing effect. If the molar ratio Li ₂ O/K ₂ O is outside the above range, the glass may become thermally unstable and may be easily devitrified during melting or firing. Note that "Li ₂ O/K ₂ O" refers to the value obtained by dividing the Li ₂ O content by the K ₂ O content.

MgO, CaO, SrO, BaO and ZnO are components that expand the vitrification range and improve weather resistance. MgO + CaO + SrO + BaO + ZnO is preferably 1 to 30%, more preferably 3 to 20%, and even more preferably 5 to 15%. If the content of MgO + CaO + SrO + BaO + ZnO is too low, the viscosity (softening point, etc.) of the glass increases, making it difficult to seal at low temperatures. It may also be difficult to vitrify. On the other hand, if the content of MgO + CaO + SrO + BaO + ZnO is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. In addition, the weather resistance tends to decrease and the thermal expansion coefficient tends to become too high.

MgO is a component that broadens the vitrification range and improves weather resistance. The content of MgO is preferably 0 to 25%, more preferably 0 to 20%, even more preferably 0 to 10%, and particularly preferably 1 to 7%. If the MgO content is low, vitrification may be difficult. Furthermore, the viscosity (softening point, etc.) of the glass may increase, making sealing at low temperatures difficult. On the other hand, if the MgO content is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. Furthermore, the weather resistance is likely to decrease and the thermal expansion coefficient tends to become too high.

CaO is a component that broadens the vitrification range and improves weather resistance. The CaO content is preferably 0-25%, more preferably 0-20%, even more preferably 0-10%, and particularly preferably 1-7%. If the CaO content is low, vitrification may be difficult. Furthermore, the viscosity (softening point, etc.) of the glass may increase, making sealing at low temperatures difficult. On the other hand, if the CaO content is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. Furthermore, the weather resistance is likely to decrease and the thermal expansion coefficient tends to become too high.

SrO is a component that broadens the vitrification range and improves weather resistance. The SrO content is preferably 0-25%, more preferably 0-20%, even more preferably 0-10%, and particularly preferably 1-7%. If the SrO content is low, vitrification may be difficult. Furthermore, the viscosity (softening point, etc.) of the glass may increase, making sealing at low temperatures difficult. On the other hand, if the SrO content is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. Furthermore, the weather resistance is likely to decrease and the thermal expansion coefficient tends to become too high.

BaO is a component that broadens the vitrification range and improves weather resistance. The BaO content is preferably 0-25%, more preferably 0-20%, even more preferably 0-10%, and particularly preferably 1-7%. If the BaO content is low, vitrification may be difficult. Furthermore, the viscosity (softening point, etc.) of the glass may increase, making sealing at low temperatures difficult. On the other hand, if the BaO content is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. Furthermore, the weather resistance is likely to decrease and the thermal expansion coefficient tends to become too high.

ZnO is a component that broadens the vitrification range and improves weather resistance. The ZnO content is preferably 0-25%, more preferably 0-20%, even more preferably 0-10%, and particularly preferably 1-7%. If the ZnO content is too low, vitrification becomes difficult. In addition, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult. On the other hand, if the ZnO content is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. In addition, the weather resistance tends to decrease and the thermal expansion coefficient tends to become too high.

_TiO2 and _Al2O3 are components _that improve weather resistance. The content of _TiO2 + _Al2O3 is preferably 0 to 10 _% , more preferably 0.1 to 8%, further preferably 1 to 6%, and particularly preferably 2 to 5 _% . If the content of _TiO2 + _Al2O3 is too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

Al ₂ O ₃ is a component that improves weather resistance. The content of Al ₂ O ₃ is preferably 0 to 10%, more preferably 0.1 to 8%, further preferably 1 to 6%, and particularly preferably 2 to 5%. If the content of _{Al 2} O ₃ is too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

_TiO2 is a component that improves weather resistance. The content of TiO2 is preferably 0 to 8%, more preferably 0.1 to 6%, further preferably 1 to 5 _{%, and particularly preferably 2 to 4%. If the content of TiO2 is} too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

CuO is a component that reduces the viscosity (softening point, etc.) of glass and also reduces the thermal expansion coefficient. It is also a component that increases the adhesive strength between glass and metal when sealing metal. The mechanism for increasing adhesive strength is currently unclear, but since Cu atoms have high diffusivity, it is thought that Cu atoms diffuse from the surface layer of the metal to the inside, making it easier for glass and metal to be integrated. There is no particular restriction on the type of metal to be sealed, but examples include iron, iron alloys, nickel, nickel alloys, copper, copper alloys, aluminum, and aluminum alloys. The content of CuO is preferably 0 to 30%, more preferably 0 to 10%, even more preferably 0.1 to 5%, and particularly preferably 0.5 to 3%. The content of CuO when sealing metal is preferably 1 to 30%, more preferably 1 to 20%, even more preferably 3 to 15%, and particularly preferably 5 to 10%. If the CuO content is too high, the glass becomes thermally unstable, and metallic Cu may precipitate from the glass surface during the sealing process, adversely affecting the sealing strength and electrical properties. In addition, the glass is prone to devitrification during melting or firing.

_WO3 is a component that reduces the thermal expansion coefficient. The content of _WO3 is preferably 0 to 20%, 0.1 to 10%, and particularly preferably 1 to 5%. If the content of _WO3 is too high, the glass becomes thermally unstable, the glass becomes more likely to devitrify during melting or firing, and the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

P ₂ O ₅ is a component that forms a glass network and thermally stabilizes the glass. The content of P ₂ O ₅ is preferably 0 to 10%, more preferably 0.1 to 5%, further preferably 0.2 to 2%, and particularly preferably 0.5 to 1%. If the content of _{P 2} O ₅ is too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult and weather resistance easily decreases.

_Fe2O3 is _a component that enhances the reactivity with the material to be sealed. The content of _{Fe2O3 is} preferably 0 to 25%, more preferably 0 to 20%, further preferably 0 to 10%, and particularly preferably 1 to 7%. If the content of _{Fe2O3 is} too high, vitrification becomes difficult and the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

Ag ₂ O is a component that reduces the viscosity (softening point, etc.) of glass. The content of Ag ₂ O is preferably 0 to 10%, more preferably 0 to 5%, further preferably 0 to 3%, and particularly preferably 0 to 2%. If the content of Ag ₂ O is too high, the glass becomes thermally unstable and is prone to devitrification during melting or firing. In addition, there is a risk that metallic Ag will precipitate from the glass depending on the firing atmosphere.

AgI is a component that reduces the viscosity (softening point, etc.) of glass. The AgI content is preferably 0-10%, more preferably 0-5%, even more preferably 0-2%, and particularly preferably 0-1%. If the AgI content is too high, the thermal expansion coefficient tends to be too high.

Nb ₂ O ₅ is a component that thermally stabilizes glass and enhances weather resistance. The content of Nb ₂ O ₅ is preferably 0 to 10%, more preferably 0 to 5%, further preferably 0 to 2%, and particularly preferably 0 to 1%. If the content of Nb ₂ O ₅ is too high, the viscosity (softening point, etc.) of the glass increases, making low-temperature sealing difficult.

V ₂ O ₅ is a component that forms a glass network and reduces the viscosity (softening point, etc.) of the glass. The content of _{V 2} O ₅ is preferably 0 to 10%, more preferably 0 to 5%, even more preferably 0 to 3%, and still more preferably 0 to 2%. If the content of _{V 2} O ₅ is too high, the glass becomes thermally unstable, and the glass is likely to devitrify during melting or firing, and the weather resistance is likely to decrease.

Ga ₂ O ₃ is a component that thermally stabilizes the glass and enhances the weather resistance, but is very expensive, so its content is preferably less than 0.01%.

_GeO2 , _Nb2O5 , _CeO2 , _Sb2O3 , _{and La2O3} are components _that thermally stabilize the glass and suppress devitrification, and each can be added up to less than 5%. If the content of these is too _high , the glass becomes thermally unstable and is prone to devitrification during melting or firing.

For environmental reasons, it is preferable that the glass composition of the present invention contains substantially no PbO. Here, "substantially no PbO" refers to the case where the content of PbO in the glass composition is less than 0.1%.

The sealing material of the present invention contains glass powder made of the above glass composition. The sealing material of the present invention may contain a refractory filler powder in order to improve the mechanical strength or adjust the thermal expansion coefficient. The mixing ratio is preferably 40 to 100 volume % of glass powder and 0 to 60 volume % of refractory filler powder, more preferably 50 to 99 volume % of glass powder and 1 to 50 volume % of refractory filler powder, even more preferably 60 to 95 volume % of glass powder and 5 to 40 volume % of refractory filler powder, and particularly preferably 70 to 90 volume % of glass powder and 10 to 30 volume % of refractory filler powder. If the content of the refractory filler powder is too high, the proportion of the glass powder becomes relatively small, making it difficult to ensure the desired fluidity.

The refractory filler powder preferably contains Zr ₂ WO ₄ (PO ₄ ) _2. Zr ₂ WO ₄ (PO ₄ ) ₂ is unlikely to react with the glass powder according to the present invention, and has the property of significantly reducing the thermal expansion coefficient of the sealing material.

In addition, the sealing material of the present invention may use a refractory filler powder other than Zr ₂ WO ₄ (PO ₄ ) ₂ as the refractory filler powder. As the other refractory filler powder, powders consisting of NbZr (PO ₄ ) ₃ , Zr ₂ MoO ₄ (PO ₄ ) ₂ , Hf ₂ WO ₄ (PO ₄ ) ₂ , Hf ₂ MoO ₄ (PO ₄ ) ₂ , zirconium phosphate, zircon, zirconia, tin oxide, aluminum titanate, quartz, β-spodumene, mullite, titania, quartz glass, β-eucryptite, β-quartz, willemite, cordierite, Sr _0.5 Zr ₂ (PO ₄ ) ₃ , etc. may be used alone or in combination of two or more.

It is preferable that the refractory filler powder is approximately spherical. In this way, when the glass powder softens, the fluidity of the glass powder is less likely to be hindered by the refractory filler powder, and as a result, the fluidity of the sealing material is improved. It also makes it easier to obtain a smooth glaze layer. Furthermore, even if a part of the refractory filler powder is exposed on the surface of the glaze layer, the stress of this part is dispersed because the refractory filler powder is approximately spherical. As a result, even if the sealed object comes into contact with the glaze layer during sealing, undue stress is less likely to be applied to the sealed object, making it easier to ensure airtightness.

The average particle diameter _D50 of the refractory filler powder is preferably 0.2 to 20 μm, particularly preferably 2 to 15 μm. If the average particle diameter _D50 is too large, the sealing layer tends to be thick. On the other hand, if the average particle diameter _D50 is too small, the refractory filler powder dissolves into the glass during sealing, and the glass tends to devitrify.

In the sealing material of the present invention, the softening point is preferably 350°C or less, particularly preferably 340°C or less. If the softening point is too high, the viscosity of the glass increases, and the sealing temperature rises, which may cause deterioration of the element due to the heat during sealing. The lower limit of the softening point is not particularly limited, but is practically 180°C or more. Here, the "softening point" refers to a value measured by a macro-type differential thermal analyzer using a sealing material having an average particle size _D50 of 0.5 to 20 μm as a measurement sample. The measurement conditions are that the measurement is started from room temperature and the heating rate is 10°C/min. The softening point measured by the macro-type differential thermal analyzer refers to the temperature (Ts) of the fourth bending point in the measurement curve shown in FIG. 1.

In the sealing material of the present invention, the thermal expansion coefficient in the temperature range of 30 to 150° C. is preferably 20×10 ⁻⁷ /° C. to 200×10 ⁻⁷ /° C., more preferably 30×10 ⁻⁷ /° C. to 160×10 ⁻⁷ /° C., even more preferably 40×10 ⁻⁷ /° C. to 140×10 ⁻⁷ /° C., and particularly preferably 50×10 ⁻⁷ /° C. to 120×10 ⁻⁷ /° C. If the thermal expansion coefficient is outside the above range, the sealed portion becomes prone to damage during or after sealing due to the difference in thermal expansion with the sealed material.

Next, we will explain an example of a method for producing and using the glass powder and sealing material according to the present invention.

First, raw material powders prepared to obtain a desired glass composition are melted at 800 to 1000°C for 1 to 2 hours until a homogeneous glass is obtained. Next, the obtained molten glass is formed into a film or the like, and then crushed and classified to produce glass powder. The average particle size _D50 of the glass powder is preferably about 1 to 20 μm. If necessary, various fire-resistant filler powders are added to and mixed with the glass powder to prepare a sealing material.

Next, a vehicle is added to the sealing material and kneaded to prepare a sealing material paste. The vehicle mainly consists of an organic solvent and a resin, and the resin is added to adjust the viscosity of the paste. If necessary, surfactants, thickeners, etc. can also be added.

The organic solvent is preferably one that has a low boiling point (for example, a boiling point of 300° C. or less), leaves little residue after firing, and does not alter the glass, and the content is preferably 10 to 40% by mass. As the organic solvent, it is preferable to use propylene carbonate, toluene, N,N'-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolidinone (DMI), dimethyl carbonate, butyl carbitol acetate (BCA), isoamyl acetate, dimethyl sulfoxide, acetone, methyl ethyl ketone, etc. Furthermore, it is more preferable to use a higher alcohol as the organic solvent. Since higher alcohols themselves have viscosity, they can be made into a paste without adding a resin to the vehicle. Furthermore, pentanediol and its derivatives, specifically diethylpentanediol (C ₉ H ₂₀ O ₂ ), also have excellent viscosity and can be used as a solvent.

The resin preferably has a low decomposition temperature, leaves little residue after firing, and is not likely to alter the glass, and its content is preferably 0.1 to 20% by mass. The resin preferably used is nitrocellulose, polyethylene glycol derivatives, polyethylene carbonate, acrylic esters (acrylic resins), etc.

Then, the sealing material paste is applied to the sealing points of the objects to be sealed, which are made of metal, ceramic, or glass, using an applicator such as a dispenser or screen printer, dried, and glazed at 300 to 350°C. After that, another object to be sealed is brought into contact with the object and heat-treated at 350 to 400°C, causing the glass powder to soften and flow, sealing the two objects.

The glass powder according to the present invention can be used for purposes other than sealing, such as coating and filling. It can also be used in forms other than paste, such as powder, green sheets, tablets (powder material sintered into a specified shape), etc.

The present invention will be described in detail based on examples. Table 1 shows examples of the present invention (samples No. 1 to 10) and comparative examples (samples No. 11 and 12).

First, raw material powders prepared to obtain the glass compositions shown in the table were placed in a platinum crucible and melted in air at 800 to 1000° C. for 1 to 2 hours. The molten glass was then formed into a film using a water-cooled roller, and the film-like glass was pulverized using a ball mill and then passed through a sieve with 75 μm openings to obtain glass powder with an average particle size D ₅₀ of about 10 μm.

Then, the obtained glass powder and the refractory filler powder were mixed as shown in the table to obtain a mixed powder.

_The refractory filler powder used was roughly spherical _Zr2WO4 ( _PO4 ) ₂ (referred to as ZWP in the table) and NbZr( _PO4 ) ₃ (referred to as NZP in the table). The average particle size _D50 of the refractory filler powder was about 10 μm.

Samples No. 1 to 12 were evaluated for glass transition point, thermal expansion coefficient, softening point, fluidity, and weather resistance.

The glass transition point and the thermal expansion coefficient in the temperature range of 30 to 150°C were evaluated as follows. First, the mixed powder was placed in a rod-shaped mold and press-molded, and then sintered at 380°C for 10 minutes on an alumina substrate coated with a release agent. The sintered body was then processed into a specified shape and measured using a TMA device.

The softening point was measured using a macro differential thermal analyzer, and the fourth bending point was taken as the softening point. The measurement was performed in air, the heating rate was 10°C/min, and the measurement was started from room temperature.

The fluidity was evaluated as follows: A mass of the mixed powder corresponding to the composite density was placed in a mold with a diameter of 20 mm, press molded, and then fired on a glass substrate at 380°C for 10 minutes. Fired bodies with a flow diameter of 19 mm or more were rated as "○", and those with a flow diameter of less than 19 mm were rated as "×".

Weather resistance was evaluated by an accelerated deterioration test using the PCT (Pressure Cooker Test). Specifically, the fired bodies prepared above were kept in an environment of 121°C, 2 atm, and 100% relative humidity for 24 hours, and then visually observed to determine whether there was any precipitate on the surface of the fired bodies, and whether there was an "O" or "X" rating otherwise.

As is clear from the table, samples No. 1 to No. 10 were evaluated as having good fluidity and weather resistance. On the other hand, sample No. 11 did not vitrify because the content of B ₂ O ₃ in the glass composition was high. Sample No. 12 had poor weather resistance because it did not contain B ₂ O ₃ in the glass composition.

The glass composition of the present invention is suitable for sealing quartz crystal oscillator packages, and is also suitable for sealing airtight packages of semiconductor integrated circuits, flat panel displays, glass terminals for LEDs, aluminum nitride substrates, etc. It can also be used as a sealing material for metals.

Claims (8)

A sealing material comprising: 40 to 100 volume % of glass powder made of a glass composition containing, in mole percent, 1 to 20% B ₂ O ₃ , 40 to 80% TeO ₂ , 5 to 30% MoO ₃ , and 10 to 30% Li ₂ O + Na ₂ O + K ₂ O , and substantially no PbO ; and 0 to 60 volume % of a fire-resistant filler powder. 2. The sealing material according to claim 1 , wherein the content of MgO+CaO+SrO+BaO+ZnO in the glass composition is 0 to 30 mol %. 3. The sealing material according to claim 1 , wherein the content of TiO ₂ +Al ₂ O ₃ in the glass composition is 0 to 10 mol %. 4. The sealing material according to claim 1, wherein the glass composition contains, in mole percent, CuO 0-30%, WO ₃ 0-20%, P ₂ O ₅ 0-10%, and Fe ₂ O ₃ 0-10%. 5. The sealing material according to claim 1, wherein the refractory filler powder is substantially spherical. The sealing material according to any one of claims 1 to 5 , characterized in that all or a part of the refractory filler powder is Zr ₂ WO ₄ (PO ₄ ) ₂ . The sealing material according to any one of claims 1 to 6 , which is used for a quartz crystal oscillator package. A sealing material paste comprising the sealing material according to any one of claims 1 to 7 and a vehicle.